Indirect metal extrusion



Dec. 20, 1960 w. scRlBNER 2,965,228

INDIRECT METAL EXTRUSION Filed May 27.- 1957 FIG-4 50 fl 36 BY ATTORNEY Unitedstates Patent 9 INDIRECT METAL EXTRUSION Albert W. Scribner, 89 Grennan Road, West Hartford, Conn.

Filed May 27, 1957, Ser. No. 661,767

2 Claims. (Cl. 207-3) This invention relates to the die expressing of metals and more particularly relates to a novel means and method for the extruding of relatively large diameter tubular products.

Conventional extrusion devices are limited in their capacity for producing large diameter tubular products. This is due in part to the fact that the operating plunger or punch has an operative diameter which is substantially equal to the inside diameter of the tube to be produced. In such an arrangement the cross sectional area of the punch can not be made too large otherwise the operative forces which must be applied to said punch will become excessively large and the high ratio of radial displacement of the work metal to punch displacement will tend to restrict the efficient fiow of the billet material.

One object of the instant invention is to provide a novel means and method for efiiciently die expressing relatively large diameter tubular products with a relatively small size punch.

Another object of the invention is to provide a novel extrusion device which is capable of producing a relatively large size product from a relatively small size billet.

Still another object of the invention is to provide a novel construction for an extrusion press whereby the radial outward flow of the metal being worked may be more efiiciently controlled and the operative forces required to be applied to the punch may be relatively small. Other objects will appear as the disclosure progresses.

In the drawings:

Figure 1 is an axial sectional view showing the principal parts of a conventional type extrusion press.

Figures 2 and 3 are axial sectional views showing the principal parts of an extrusion press which is constructed in accordance with the principles of the instant invention.

Figures 4 and 5 are axial sectional views showing the principal part of two modified embodiments of the instant invention.

In the conventional type extrusion press illustrated in Fig. l the die block 20 is formed with a cylindrical recess 22 having a bottom wall 36 and cylindrical side walls 24. The walls 24 cooperate with the outer cylindrical surface formed at the lower end of an axially movable punch 12 to thereby define an annular extrusion die orifice 14 through which the work metal flows to form the tubular product 16. It will be seen that as the inner and outer radial dimensions of the annular orifice 14 are made larger so as to permit the extruding of larger sized tubular products, longer radial displacements of the work metal are required to accommodate the relatively short axial working stroke of punch 12. This high ratio of metal displacement to punch displacement not only tends to decrease the control possible over the metal fiow patterns occurring during the extrusion action but also requires the application of excessively high working forces to the punch. This latter condition increases the difficulty of maintaining the punch 12 and die block 20 in continuing coaxial relation during the extrusion operation so that the shape of the die orifice 14 remains fixed.

Referring to Fig. 2 there is shown one embodiment of the instant invention. Here the cylindrical side walls 24 of the die block 20, which is similar to that just described in Fig. 1, cooperate with the outer cylindrical surface 26 formed on the lower end of a movably supported tubular member 28 to thereby define an annular die orifice 30. The tubular member 28, which may be considered as a container or a hollow billet receiving plunger, is provided with an axially extending cylindrical bore or chamber in which is slidably mounted a working ram 32. Ram 32 is operative to progressively displace work material downwardly through said bore and radially outward between the lower radial end face 34 of the tubular member 28 and the bottom 36 of the die block recess 22 and then upwardly through the annular die orifice 30 in a direction which is opposite to that of the downward working stroke of ram 32 so as to thereby form the tubular extruded product 38 as illustrated in Fig. 3. The outside cross sectional profile of the tubular extruded product is substantially the same as the profile of the recess side walls 24 in said die block 20, while the inside cross sectional profile of said product is substantially the same as the profile of the outer surface 26 of said tubular member 28. In this type of structural and functional arrangement the tubular member 28 acts as a billet container and partially defines the extrusion orifice 30, as Well as serving as a mandrel in determining the inside diameter of the extruded product.

In the operation of the press shown in Fig. 2 the ram 32 is withdrawn and a work billet B is inserted into the tubular member 28 which is then operatively positioned with respect to the cylindrical side walls 24 of the recessed die block 20. Thereafter the ram 32 is advanced to thereby die express the work metal during which time the tubular member 28 is either held stationary relative to the die block 20 or is advanced a short distance relative to the die block and in timed relation to the movement of said ram 32. Both the ram 32 and the tubular member 28 are then retracted and the tubular extruded product 38 stripped from the outer surfaces of said tubular member by any suitable means. It will be noted that the minimum radial dimension of the annular orifice 38 is greater than the maximum radial dimension of the billet B. Ram 32 may be advanced at conventional operative speeds or may be advanced rapidly to thereby effect an impact extrusion of the work billet.

The operative cross sectional area of the ram 32 may be made substantially equal to the area of the orifice 30 whereby the length of an operative working stroke of the ram will be substantially equal to the axial length of the tubular product 38 thereby produced. If the operative cross sectional area of the ram is made greater or less than the area of orifice 30, then the length of an operative working stroke of ram 32 will be less or greater, respectively, than the axial length of the tubular product thereby formed. It will be apparent that the smaller the cross sectional area of the ram 32 is made the longer will be its operative stroke to produce a given size extruded product, and the smaller will be the force required to displace the ram.

Fig. 4 shows a modified form of the invention. Here the principal parts of the extrusion press are similar in nature and operation to that shown in Figs. 2 and 3 except that the lower end of the ram 40 has been reduced in diameter as shown at 42. The surfaces of this reduced portion of the ram in cooperation with the inner walls of the tubular member 28 will define a second annular die orifice 46 whereby multiwalled tubular products may be die expressed.

The embodiment of the invention illustrated in Fig; is similar in nature to that'illustrated in Figs. 2 and 3 except that here the lower surface 50 of the tubular member 52 is contoured so that'the areas of th'esurfac'es of revolutions, about the axis of said member 52 of the successive distances d between the bottom Wall 36 of the die block recess 22 and said surface SO'decrease' at a substantially constant percentage rate; the distances at being taken substantially normal to the radial flow'62' of the work metal. This contouring will decrease the tendency for the work material to separate along radial lines due to the circumferential tension created in the metal by its outward movement in all radial directions during the extrusion operation. The areas of said surfaces of revolution may remain constant whereby there will be little if any actual reduction of the work material as it flows radially outward. If desired this constant area may be made substantially equal to the area of the die orifice 30 whereby most of the actual reduction of the work metal occurs near the center of the press and just beneath the lower face of the working ram 70. 7

Having described the principles of the invention, I claim:

1. In an extrusion press; a die block having a recess formed therein, said recess having a bottom wall and cylindrical side walls, a tubular member mounted above said recessed die block for cooperation with the latter, said tubular member having a billet receiving cylindrical bore formed therethrough and being formed at its lower end with a die forming outer cylindrical surface, the radial dimensions of the cylindrical surface of said tubular member being less than the radial dimensions of the cylindrical side walls of said die block recess, said tubular member being operatively disposed with respect to said die block such that said outer cylindrical surface together with said cylindrical side walls cooperatively define an annular extrusion orifice which extends longitudinally of and around said outereylinnriealsurface ofsa'id tubular member, said bore being adapted to receive a Work billet having outside radial dimensions which are less than said bore and the inside radial dimensions of the tubular extruded product to be formed whereby when the ram is displaced through a downward working stroke said ram will progressively displace the billet material down through said'bore and then radially outwardly between the bottom wall of said recess and the end face at the bottom of the lower end of' said" tubular member and finally upwardly through said annular extrusion orifice in a direction which is substantially opposite to the downward movement of the ram so as to thereby form a relatively large tubular extruded product 2. Apparatus as defined in claim 1 wherein the spacing between the said bottom wall of said recess and the lower end face of said tubular member is such that the areas of the respective surfaces of revolution of' the lines progressively defining the thickness of the radially flowing work metal decrease at a substantially constant percentage rate.

References Cited in the file of this patent UNITED STATES PATENTS 

